Process for treating oil



Feb. 20, 1940. u. B. BRAY ET A1.

PROCESS FOR TREATING GIL Original Filed Aug. 4, 1931 Patented Feb. 20, 1940 PATENT OFFICEl PROCESS FOB TREATING OIL Ulric B. Bray, .Palos Verdes Estates, and Claude E. Swift, Glendale, Calif., assignors to Union Cil Company of California, Los Angeles, Calif., a corporation oi' California Griginal application 'August 4, 1931, Serial No.

Divided and this application June 12,

1934, Serial No. 730,217

Claims.

This invention relates to a method and apparatus for treating petroleum to produce lubricating oil. 'I'his invention is a division of our co-pending application, Serial No. 555,018, filed August 4, 1931 and which has issued as Patent 2,006,092, June 25, 1935.

One of the distinctive characteristics of a lubrieating oil is its viscosity. For many purposes lubricants are preferred which exhibit a minimum variation in viscosity with variations in temperature, i. e., have low viscosity temperature susceptibility. It is generally known that the viscosity of lubricating oil produced from Western crude, such as California naphthene base crudes, that is, crude containing asphalt varies more with change in temperature than do lubricating oils produced from paraiiin base crudes.

That is. if two such oils have the same viscosity at 100 F., the Western oil will have a much lower viscosity at 210 F. than will the parailin base oil. This change in viscosity with temperature is sometimes called the temperature viscosity susceptibility of an oil. It is one of the characteristics of Western lubricating oils that they are distillates, that is, are vaporized from crude oil and condensed. Lubricating oils produced from parailln base oils, containing substantially no asphalt, are generally produced by first distilling light oils overhead, including the kerosene and gas-oil and also taking overhead light lubricating oils called neutrals having a viscosity in the neighborhood of 100-200 seconds, Saybolt Universal at 100 F., leaving an undistilled residue termed bright stock. The oils of various viscosity are made by blending these` neutrals and bright stock in any desired proportion to obtain the desired viscosity.

It has been observed by one of us that many oils containing asphalt and wax are mixtures of hydrocarbons analogous both to the hydrocarbons present in paraiiin base oils and those present in asphalt base oils. It has further been observed by one of us that during the heating of `an oil containing asphalt, the asphalt apparently induces certain chemical and perhaps certain physical reactions at relatively low temperatures which tend to destroy the inherent low viscosity temperature susceptibility of the lubricating oil fractions. This apparent catalytic phenomenon seems to explain the observed changes although we do not wish to be understood as being bound by this theory. It has been observed that these temperatures at which the changes appear are below the vaporizing temperatures in batch distillation (vacuum or steam) of the lubricating (Cl. 19E-40) oil fractions which have Saybolt Universal viscosities above 400-500 seconds at 100 F. It is safe to say that no oil containing asphalt can be topped to the point where fractions above 400-500 seconds, Saybolt Universal viscosity at 100 F. are vaporlzed without a degeneration of those characteristics of the paramn hydrocarbons which impart to the oil a low temperature viscosity susceptibility. During the distillation of the heavy oils in the presence of asphalt some change in molecular structure or conilguration takes place which is attended by a change of viscosity temperature characteristics. This behavior is thought to be due to pyrolytic reactions which are catalyzed by the presence of asphalt. The above discovery is made.A the subject matter of application Serial No. 466,189, led July 7, 1930, by Ulric B. Bray.

In order to preserve the inherent characteristics of the lubricating oil components of crude oil containing asphalt which are impaired by distillation methods as previously described, we have, in accordance with the process of the above application, caused the separation of the oil and wax from the asphalt by a method wherein the lubricating oil constituents present in the crude oil are separated from the asphalt present in such a manner that the oil retains those characteristics which it possessed in the original crude oil. As a means of attaining this end it has been found advisable to cause the separation of the asphalt from the oil by means of solvents which are capable of dissolving the oil and which do not dissolve the asphalt. Such solvents are light petroleum fractions, such as naphtha, casinghead gasoline and petroleum fractions normally vaporous at ordinary temperature and4 pressure. Other solvents which may be used are alcohol, ether, mixtures of alcohol and ether, acetone, etc. We prefer to use as our solvent a petroleum fraction obtained by the rectication of natural gasoline. For most purposes a fraction composed of 6.72% ethane, 72.2% propane, 19.91% isobutane and 1.17% normal butane is satisfactory and is an example of commercially obtainable propane. This fraction is characterized by an average molecular weight and an average vapor pressure substantially the molecular weight and vapor pressure of pure propane. It will be understood, however, that these merely illustrate the type of fractions which maybe used and'that the composition may vary. This fraction will hereinafter be referred to as propane for purposes of simplicity. It is obvious that pure propane or commercial propane, i. e., propane contaminated with methane. ethane, propylene. butano and the like, are equally apphcable for use in our process. In carrying out the extraction oi.' the, oil with this light liquid fraction the solution is maintained at a pressure sumcient to maintain the propane liquid at ordinary temperatures. The traction described above is liquid at ordinary temperatures at a pressure oi about 125 pounds per square inch. 'Ihe extraction of the oil from the petroleum at such pressures' results in an asphalt substantially free oi.' oil consisting chieyI oi pure bitumen and a solution of oil and wax in the liquid petroleum fractions. The oil dissolved in the liquid propane contains substantially all oi the lubricating oil components which are present inthe crude oil and in substantially the same form as they exist in the originalcru'de oil and also the mador portion of the wax present in the crude oil.

We have discovered that many lubricating oils obtained by extraction with solvents, for instance, propane, from crude oil containing asphalt and wax are composed of oils which have a relatively high temperature viscosity susceptibility and oils which have a relatively low temperature viscosity susceptibility and that these oils may beseparated into oils which exhibit a low temperature viscosity susceptibility resembling oils produced from non-asphalt containing crude and oils which exhibit a high temperature viscosity susceptibility corresponding to oils produced by distillation. For `convenience we will call the oils which exhibit a low temperature viscosity susceptibility parafiinoid and those which exhibit a high temperature viscosity susceptibility and resemble the Western lubricating oil distillates nonparaftlnoid. The 'propane extract which consists of such a mixture -oi? parafllnoid and non-parafllnoid oils may be separated into these respective oils by the use of solvent agents which will selectively dissolve out the non-paramnoid components. We have i'ound that certain solvents have a selective solvent action for the non-paraflinoid oils. As solvent agents which will effect this separation we have found liquid sulphur dioxide, mixtures of acetone and 'benzoL aniline or methyl formate useful. Acetone alone, in addition to being an asphalt precipitant, also has in some measure the ability to split the oil in the above manner. The use of liquid sulphur dionde has been found especially valuable as a solvent to separate the propane extract into oils which exhibit low temperature viscosity susceptibility and into oils which exhibit high temperature viscosity susceptibility.

As the propane extract from the crude oil consists oi' a mixture of wax and oil normally solid at ordinary temperatures, it cannot be separated a into its paramnoid and non-parafllnoid components by the use of sulphur dioxide, without considerable diillculty, unless dissolved in a carrying medium. We have found it advantageous to carry out the extraction of the wax oil mixture with sulphur dioxide in the presence of the liquid propane used in separating the asphalt. The wax oil mixture is dissolved in liquid propane after which it is extracted with liquid sulphur dioxide to remove therefrom the non-parai'iinoidl components. The propane solution oi' parafiinoid oil is then chilled to precipitate thel wax present after which the chilled mass is cold settled, centrifuged, orv filtered to separate the wax from the propane solution of oil. By removing the sulphur dionde soluble bodies from the propane solutionl ci waxy oil prior to the c waxing operation' we are abletoobtain a iii' product with-alwer pour point, i. e., wax cc tent than could be obtained if the sulphur dic ide extraction operation were performed, suba quent to wax removal.v The sulphur dioxide i moves from oil certain bodies present which s good wax solvents and which have a tendency prevent precipitation of the wax during the c waxing operation.

The propane solution or oil recovered from t dewaxing operation substantially free oi a phalt and wax may be further purined by tres ment with sulphuric acid. Such treatment i moves from the paramn oil further impuriti which were not removed from the oil by the tree ment with liquid sulphur diende.

Generally stated, it is the object of our inve tion to isolate from crude oil those oils havii characteristics which impart to it the low tex perature viscosity susceptibility typical ot'para iin base oil.

More particularly, it is an object oi' our inve tion to isolate from asphalt containing oils thc components which impart to the oil the reduc susceptibilityto change inviscosity with ten perature which is characteristic oi oils obtaim from non-asphalt containing oils; that is, to se] arate the parailinoid from the non-paraillno components of the asphalt containing crude oli It is a further object of our invention to se] arate asphalt from an oil containing aspha oil and wax by means of a solvent, to separa the wax and parailinoid oil from the non-para nnoid oil by means of a second solvent used the presence of the iirst solvent, to separate tl wax from the parailinoid oil and thereafter treat the paraiiinoid oil dissolved in said 'r solvent with sulphuric acid. l

It is a further object of our invention to se] arate oil and wax from an oil containing asphal oil and wax by the use of liquid propane; to sel arate the wax and parailinoid oil from the nor paraiiinoid oil by the use oi liquid sulphur d oxide in the presence of liquid propane; to se; arate the wax from the parailinoid oil an thereafter to treat the paralnoid oil with sul phuric acid.l

The drawing represents one form of apparati which we may employ to' carry out our proces Referring more particularly to the drawing, vtl: crude oil which has been distilled to remove ligl: oils such as gasoline and kerosene and is itsei a residual oil containing lubricating fractiom asphalt and wax in tank I is withdrawn througl valve 2 and 'sent by means of pump 3 througl line 4 where it meets a stream of liquid propan coming from tank ill through valve vii, line Ii pump Il! and line I2'. The mixture of toppe crude and liquid propane passes from line 4 t chiller i where a portion of the propane is. al lowed to vaporize through valve 6 and passes b means of line 'I to pump 32 where it is compresse and sent to condenser 8 where it is liquefied am sent by means of line 9 to storage tank I0. Th vaporization of the propane in chiller 5 cause the temperature of the mass therein to be low ered. `The cool mass from chiller 5 passes b; means of line I3 to agitator I4 where itis, thr oughly mixed and sent by means of line lit decanter II where the asphalt is allowed to set tle out.

The asphalt is withdrawn from decanter Il through valve i1 and sent by means of pump il throughline l! to heater 2t where the propam and moisture are vaporized. The heated mass passes from heater through line 2l to separator 22 where the asphalt separates from the vapors and is withdrawn through valve 23 and line 24 in the storage tank 28. The vapors in separator 22 are withdrawn through line 28 into condenser 21 where the water vapor present is condensed. The condensed water and propane vapor pass into separator 28 where the water separates and is withdrawn through valve 29 and line 30. Propane vapor passes from sep-` arator 28 through line 3| to compressor ||3 thence to condenser 8 where it is liquefied and passes by means of line 9 toV storage tank I0.

The solution of oil in liquid propane in decanter I8 is withdrawn through line 33 and sent to chiller 34. A portion of the propane present is allowed to vaporize by opening valve and allowing the vapors to pass through line 36 to compressor ||8 where it is compressed and sent to condenser 8 and is liquefied, thereafter being sent to storage tank I0. The vaporization of the propane in chiller 34 cools the mass which is thereafter withdrawn through valve 31, line 38 and sent by means of pump 39 through line 40 to the lower zone of extracton column 4|. Liq-l i uid sulphur dioxide from tank 42 is withdrawn through valve 43 and sent by means o! pump 44` through line 45 to the upper zone of extraction column 4|. Due to the difference in speciiic gravity of. the oil introduced through the lower zone of the extraction column and the liquid sulphur dioxide introduced into the upper zone of the extraction column, these two liquids tend to separate. As the liquid sulphur dioxide descends through the extraction column it dissolves certain components present in the oil.

The solution o1' liquid sulphur dioxide and oil is removed from the extraction column 4| through the valve 46 and sent by means of line 41 to vaporizer |05 where'the sulphur dioxide is vaporized by aid of steam introduced through closed coil |0| and passes through line |08 to compressor |01 where it is compressed and sent through line |08 to condenser |09 where it is liquefied and sent to storage tank 42. Sulphur dioxide free oil in vaporizer |05 is Withdrawn through valve |02 and sent through line |03 to tank |04.

The ascending column of oil in extraction co1- umn 4|, from which the liquid sulphur dioxide soluble components have been removed, passes through valve 48 to line 49 to auxiliary separator 50 where any remaining liquid sulphur dioxide is settled out. A clear solution of oil is withdrawn from auxiliary separator 50 through line 52 where it may be mixed with a further quantity of liquid propane coming from storage tank I0 through valve 53, pump ||4 and line 54. The solution of oil and propane carrying a small quantity of `sulphur dioxide passes into chiller 55 where a portion of propane is allowed to vaporize by opening valve 8|. The vaporized propane contaminated with sulphur dioxide,

Vof line ||0 to separator 90 where these two materials separate due to their great dierence in specific gravity. The liquid propane in separator 98 is withdrawn through valve 9| and sent by means of pump 93 through line 98 to storage tank |8. 'I'he liquid sulphur dioxide in separator is withdrawn through valve 92 and sent by means of pump 94 through line 98 to storage tank 42. The vaporizatlon of the propane in chiller 88 cools the remaining solution of oil present which passes out through valve 88 and line 81to pump 88 which forces it through filter press 89 where the` precipitated wax` is removed through line 80. i

The wax-tree oil from lter press 89 through line 81 where it meets a stream oi' sulphuricacid coming from tank 83 through valve 84, line 88 and pump 88. The mixture of acid and oil passes from line 81 through agitator 88 where the mass is thoroughly agitated, after whichlit passes through line 89 to separator 10 where the sludge is allowed to settle out. The sludge in separator 10 is withdrawn through valve 18, line 18, to pump 11 `.which forces it through line 18 to heater 19 where the mass is heated sufciently to vaporize the propane present. The heated mass passes from heater 19 through line 89 to separator 8| where the sludge separates from the propane and is withdrawn through valve 82 and sent through line 83 to storage 84. 'I'he propane vapor is withdrawn from separator 8| through line 85 to compressor ||2 where it is compressed and sent by means of line 88 to condenser 89 where it is liquefied and sent by means of line I|0 to separator 90 where it is separated from any liquid sulphur dioxide 'and sent by means of valve 9|, pump 93, line 96 to storage tank I0. The liquid sulphur dioxide in separator 90 is withdrawn through valve 92 and sent by pump 94 to sulphur dioxide storage tank 42.

The acid treated oil in separator 10, dissolved in propane carrying varying amounts of sulphur dioxide, is withdrawn through line 1| and passed through clay tower 12 where any remaining sludge is separated out. The fraction of oil leaving clay tower 12 passes by means of line 13 to evap orator 14 where the propane and sulphur dioxide present are vaporized by aid of steam introduced through closed coil 91 and are sent by means of line 98 to compressor 81 where they are compressed and sent by means of line 88 to condenser 89 where they are liquefied and sent by means oi.' line ||0 to separator 98. Liquid propane in separator 90 is returned to storage tank I8 through valve 9|, pump 93, and line 98. The sulphur dioxide in separator 99 is returned to storage tank 42 through valve 92, pump 94 and line 95. 'I'he oil in evaporator 14 which is free from propane and sulphur dioxide is removed through valve 98 and sent by means of line 99 to reiined oil tank |00.

As illustrative of the operation of our process for one type of oil and without intending to limit our invention, water free residual oil in tank of Fig. 1 at a temperature of about 200 F. is mixed with liquid propane and cooled by allowing a portion of the propane to vaporize under reduced pressure until the temperature of the topped oil and propane is about F. after which it is thoroughly mixed in agitator |4. The thoroughly agitated mass is then passed into decanter I8 where the propane solution of lubricating oil and wax is separated from the undissolved asphalt. This oil dissolved in liquid propane contains'a mixture of parainoid and non-paraiilnoid components. By subjecting this mixture to the selective solvent action of liquid sulphur .dioxide in the presence of liquid propane it is possible to resolve the mixture into a portion oi.' a nonparaffinoid nature soluble in liquid sulphur dioxide and a portion of a paraiiinoid nature soluble in liquid propane. The wax present in the mixture being more soluble in the liquid proatilnoid oil' and wax dissolved in liquid propane f is then chilled to a point4 suiiicient to cause precipitation of the:Y wax. after which the chilled mass is illtered. centrifuged or cold settled to remove the wax. The wax-tree solution of parafilnoid oil dissolved in the liquid propane is then treated with sulphuric acid to remove further undesirable bodies present, after which the solution formed is settled out and the propane removed by distillation from -the reilned oil.

The foregoing exemplary description is merely illustrative of a preferred mode of'r carrying out our invention and is not to be taken vas hunting, as many variations may be made within the scope of the followingclaims by a person skilled in the art without departing from the spirit thereof.

We claim:

1. A process for treating oil which comprises diluting said oil with a liquefied normally gaseous hydrocarbon diluent maintaining the diluted oil under sufficient pressure to keep the liquefied normally gaseous hydrocarbon in a liquid state, clay treating said oil and diluent and separating said clay treated oil from said diluent.

2. A process for treating lubricating oil which includes diluting the lubricating oil. with a normally gaseous liqueied hydrocarbon diluent maintained at superatmospheric pressure sumcient to maintain the diluent liquid, contacting said diluted oil with clay at such pressure and separating the treated ou dissolved in sud not ned diluent at superatmospheric pressure irc the clay, andseparating said oil from said 'diluei 3. A process for treating oil which compris diluting said oil with a liquefied normally gaseo hydrocarbon diluent maintaining the diluted l under suillcient pressure to keep the liqueil normally gaseous hydrocarbon in a liquid stm treating said oil and diluent with sulphuric ac treating said acid treated oil and diluent wi clay and separating said oil from said diluent.

'4. A process for treating oil which compris diluting said oil with a liqueied normally gaseo hydrocarbon diluent maintained at superatmo pheric pressureto maintain the diluent liqui treating said oil dissolved in said diluent wi` sulphuric acid at said pressure. contacting sa acid treated diluted oil with clay at said pre sure, separating the treated oil dissolved in sa diluent at superatmospherio pressure from tl clay and separating said oil from said diluent.

5. A process for treating mineral oil whiz includes diluting the oil with a diluent compost chiey of propane, maintaining the oil dilute with the propane under suiicient pressure to kei the propane in a liquid state. contacting the c diluted with' propane with clay, separating tl treated oil dissolved in the propane from ti clay and separating the propane from the cls treated oil.

ULRIC B. BRAY. CLAUDE E. SWlIllIe 

